The moisture resistance of articles such as garments is affected by the number and types of openings in the garment. Ideally, a water-resistant garment should be comfortable, easy to put on and take off, and allow freedom of movement. While using a zipper for a garment closure makes the garment easy to put on and take off, the zipper can reduce the water resistance of an otherwise water-resistant garment and can impact the wearer's comfort and mobility.
Slide fasteners, such as zippers, are commonly used in the garment industry. Typical zippers for jackets and other outerwear comprise metal zippers, molded zippers, and coil-type zippers. Zippers used in garments tend to be of a larger size such as a number 5, 6, or 7. Coil-type zippers are preferred for moisture resistant garments due to their strength, imperviousness to corrosion from moisture, and ease of sewing into garments.
Various features are sometimes added to conventional slide fasteners or to articles with such fasteners in order to enhance water resistance. For example, a flap may be added behind the slide fastener (on the inside of the article or garment) to physically block the penetration of water beyond the flap. This fails to prevent wetting of the stringers and teeth from the outside and can result in thickening/bulkiness of the article along the line of the fastener, which may be especially undesirable in articles such as garments. Alternatively, a water resistant coating is sometimes added to the outside of a zipper tape. While such coatings may limit the penetration of water through the tape, they do not prevent penetration of water through the interlocked teeth. It is possible to apply a coating that covers the zipper teeth. But water resistant coatings can cause stiffness of the zipper/slide fastener, resulting in an increased difficulty of operation and an unattractive appearance in articles such as garments. In addition, the repeated operation of the slider to open and close the fastener tends to abrade and/or displace the coating, resulting in the formation of a gap over the engaged teeth. This gap allows water to penetrate through the zipper teeth. Continued use of the fastener further degrades the coating and widens the gap, decreasing the effectiveness of the coating and the physical appearance of the fastener and article over time.
An example of prior art moisture resistant zippers with coated zipper chains is disclosed in U.S. Pat. No. 6,105,214. This patent discloses a zipper chain that is coated with a water resistant polyurethane layer and the method of making such chain. Zipper chain made using this method is more rigid due to the coating layer. The coating layer is pushed aside by the slider body of the zipper during normal operation of the zipper. This allows water to migrate directly through the zipper teeth at the point on the chain where the slider is located as well as some distance in either direction from the slider. In addition, repeated operation of the slider degrades the mating edges of the polyurethane layer over time, which can allow water to migrate directly through the zipper teeth along the length of the zipper chain.
Typically, manufacturers of articles that use zippers, such as garment manufacturers, purchase pre-made zipper tapes from zipper manufacturers and then mount each zipper tape to an article of clothing, such as by sewing or using adhesive films. If an adhesive film is used, it must be precisely cut (for example, using laser cutting) to accommodate the opening in the article so that adhesive is not visible between the edges of the upper layer of the finished article. Since the size of a zipper opening can vary from article to article, a manufacturer of articles that use zippers may need to cut adhesive films of various sizes to accommodate the various sizes and measurements of zipper tapes. This not only increases costs, but also complicates the garment manufacturing process.
There are typically a few general types of slide fastener construction. In a conventional non-invisible slide fastener, for example, a slider body is disposed on the exterior of the zipper tape and generally includes lateral rails to guide the coil/teeth into the slider. The top plate is connected to a bottom plate by a post that forms a rounded or diamond shape in plan view and is used to guide the zipper teeth into the slider body towards the joining area. The bottom plate generally includes a control rib to guide the zipper teeth/coils within the slider body and/or to apply pressure to the zipper teeth. This bottom control rib is shaped to separate the zipper tapes and lift the teeth/coil of each stringer into the proper orientation for engagement with the teeth/coil of the opposing stringer.
In a typical non-invisible nylon coil slide fastener, a nylon coil that forms a row of teeth is sewn to an upper surface of a strip of material (the stringer). When stringers are sewn into an article, such as a garment, the zipper teeth face outwards and the smooth (non-coil) lower surface of each stringer faces inwards toward the interior of the article. Even when the slide fastener is closed, small spaces between the interlocked teeth and the seams between the stringers and the surrounding fabric can allow water and/or air to pass from the front side to the back side of the zipper.
In contrast to the non-invisible nylon coil slide fastener, the nylon coil of a typical invisible slide fastener is coupled to the lower surface of the stringer. Again, even when the slide fastener is closed, small spaces between the interlocked teeth and the seams between the stringers and the surrounding fabric allow penetration of water and/or air through the fastener. Features added to conventional non-invisible slide fasteners may be added to invisible slide fasteners, with the same disadvantages. In addition, the top plate in the conventional invisible slide fastener slider causes the adjacent edges of the overlying fabric/material or coating to fold, bunch and/or separate as the bail moves between them during operation of the slide fastener. Over time, this wearing of the edges by the bail increases the size of the gap and can cause separation of the zipper tape from an overlying layer such as fabric, adhesive, a coating, etc.
Conventional slide fasteners may be installed in an article by various methods such as stitching/sewing or by use of an adhesive. The stringers may also be coated with a water resistant coating, as discussed above. However, the application of adhesive or coatings to zipper tapes (i.e. stringers coupled to teeth or coils) currently requires a post-manufacturing process in which a sheet of adhesive/coating is cut to match the perimeter of the zipper tape. The cutout must include an opening that matches the shape of the opening of the exposed portion of the zipper tape. The opening is generally at least the width of the slider body in order to prevent jamming of the slider. The additional steps required for post-manufacturing application of adhesives/coatings increases the expense and time required to prepare a slide fastener for installation into an article. Furthermore, this leaves a portion of the zipper tape exposed to the elements and reduces the weather resistance of the finished article.